Initial Carbonation of Ni(111) Surfaces

Area of Science:

• Surface science
• Materials science
• Catalysis

Background:

• Controlling carbon formation on nickel (Ni) surfaces is crucial for Ni-based nanofabrication and heterogeneous catalysis.
• The high solubility and complex migration of carbon in Ni present experimental challenges in understanding initial carbonation at the atomic level.

Purpose of the Study:

• To investigate the initial formation of surface carbon adsorbates on Ni(111) using the Boudouard reaction.
• To elucidate the atomic-level mechanisms governing carbon adsorption and its implications for carbide and graphene formation.

Main Methods:

• Scanning Tunneling Microscopy (STM) for atomic-scale surface imaging.
• Density Functional Theory (DFT) calculations to model carbon adsorption energetics and kinetics.
• Experimental studies extended to Ni(110) and Ni(211) surfaces under varying conditions.

Main Results:

• Initial carbon adsorption is site-selective on Ni(111): strong bonding at step edges (carbide precursor) and weaker, mobile adsorption on terraces (graphene clusters).
• The kinetics of carbon adsorption differ between step and terrace sites, influencing subsequent growth pathways.
• New evidence resolves the atomic structure of the (√39 × √39) R16.1° Ni carbide.

Conclusions:

• The study provides fundamental insights into the initial stages of carbon formation on Ni surfaces.
• Understanding site-selective adsorption and kinetics is vital for controlling the growth of nickel carbide or graphene.
• The findings offer valuable guidance for controlling carbon-nickel interactions in catalysis and nanofabrication.